LD side-pumped Nd:YAG/KTP CW laser with 1.8 W output at 659.5 nm

This letter reports the generation of 1.8 W CW 659.5 nm red laser radiation by intracavity frequency-doubling a Nd:YAG laser with a KTP crystal (type II phase match. θ=59.8°, φ=0°). A China-made high power LD side-pumping module is employed, which possesses a max power of 600 W at 808 nm, and oscillating wavelengh of Nd:YAG is confined to 1319 nm single wavelength by means of coating highly selective film. For the aim of obtaining high power of red laser, a Z-shaped resonator is designed, and the cooling temperature of KTP is lowered to 7°C to compensate the thermal effect of KTP. The generation of 1.8 W of the CW red laser beam is obtained with 317 W pumping power.